This invention relates generally to optics, and more particularly to reflective optics for use in Raman spectroscopy.
Raman spectroscopy is a powerful tool for studying properties of materials. Raman spectroscopy measures light that has been in-elastically scattered from a sample to measure properties of the sample. However, Raman scattering is a relatively weak effect, and as a consequence it can be difficult to measure small Raman signals. One particular source of noise that is particularly difficult to get rid of is errant Raman signals that may be generated by the optics that are used as part of the Raman spectroscopic system.
Errant Raman signals from the optics of the spectroscopic system get worse the more light provided. In order to obtain a useful Raman signal from a relatively weak source, a large amount light is input into the spectroscopic system in order to generate a Raman signal of measurable strength. The large amount of light will also, however, cause the optics to generate a large errant Raman signal. Thus, the problem cannot be solved by simply adding more light to the spectroscopic system.
Traditionally, this problem was solved by minimizing the use of optical elements between the light reflected from a sample being measured, and the detector detecting the Raman signals. While this works adequately in laboratory settings where space is not at a premium, this solution causes the Raman spectroscopic system to take up a great deal of space, making it impractical for many applications.
Thus, what is needed is an optical element which collects a large amount of scattered light collected from a sample and delivers it to a spectroscopic detector without passing through materials which would add their own errant Raman signature.